Suspensions for heavy vehicles, including trucks and trailers, are typically supported with leaf springs and beam suspensions, which are positioned between an axle or axle assembly and a load carrying frame. Beams and leaf springs generally terminate at each end with a circular eyelet. A bushing is inserted in each eyelet, and allows the beam or leaf spring to be mounted on a hanger or other mounting structure secured to the frame in order to mount the beam or spring on the frame.
Over time, the bushings are generally subject to wear, rust, and other environmental and mechanical stresses. In order to maintain the integrity of the vehicle, the bushings should be replaced as needed. Bushings generally have an extremely tight fit with the eyelets of the beam or leaf spring, which increases the amount of force needed to remove an old bushing and install a replacement.
One known method of servicing bushings includes disassembling the suspension in order to remove the beams or leaf springs from the vehicle, and using a hydraulic press in order to remove old bushings and install replacements. However, disassembling the suspension is costly, time consuming, mechanically intensive, and complex. Additionally, a hydraulic press large enough to support a beam or leaf spring during operation is generally expensive and complex.
Portable hydraulic bushing service tools have been developed. In one example illustrated in FIG. 1, the rear suspension bushing tool, part 4244, produced by Bosch Automotive Service Solutions, includes a first plate 1 connected to a second plate 3 via rods 2. The second plate 3 is configured to support a hydraulic cylinder 4. To operate the tool, a user positions the tool so that an inner side of the first plate 1 is positioned against a rear side of a spring or suspension beam in a region of a bushing to be serviced. While holding the tool in place, the user positions an adapter 6 between the first plate 1 and second plate 3 and then extends the hydraulic cylinder 4 until the adapter 6 is held in place between the bushing and the hydraulic cylinder 4 as illustrated in FIG. 2. Once the adapter 6 is held in place, the user can check if the tool adapter is aligned with the bushing. If the adapter 6 and cylinder 4 are not properly aligned, the user can retract the cylinder 4, and realign the cylinder 4 and adapter 6. Because the tool is not supported when the cylinder 4 is retracted, realigning the cylinder 4 and adapter 6 generally requires the user to physically support the tool. Once aligned, the cylinder 4 can then be operated to push the bushing out from the spring via the adapter 6.
To install a replacement bushing with the tool, the cylinder 4 is disengaged, and the tool is repositioned with the first plate 1 against the rear side of the beam. While holding the tool in place, the user then holds both the adapter 7 and the new bushing between the beam and the cylinder 4. The cylinder 4 is then actuated until the adapter 7 and bushing are held in place between the spring (and the cylinder 4. As above, the user can then check whether the adapter 7, cylinder 4, and bushing are aligned with the hole in the beam, and if necessary can retract the cylinder 4 to correct the alignment. Once aligned, the cylinder 4 can be operated to install the bushing in the hole.
While service tools of the type described above are portable, and are usable with a hydraulic cylinder rather than a full hydraulic press, operating such tools generally requires a user to hold the tool in place until the cylinder is at least partially engaged, and generally require manual alignment of one or more components.
The rear suspension bushing tool, part 4244 described above weighs approximately 67 lbs. Because the user must support the tool during placement and alignment, the servicing of a bushing with such a tool may be physically intensive. Since bushing servicing may be conducted multiple times per vehicle and for multiple vehicles in a day, the physical exertion needed to place and align the tool may limit its functional use. The need for the user to support the components of the tool may also limit the size of the cylinder that can be supported by a user and thus that can be used with the tool. For example, the cylinder 4 may only be able to generate approximately 15 tons of axial force, which may not be sufficient to service all types of bushings. Additionally, in the tool described above, the first plate 1 and second plate 3 are at a fixed distance from each other, and thus the tool is only usable to service springs that are sized to fit with the tool.
Therefore, what is needed is a portable bushing service tool that does not need to be held in place, that does not require manual alignment, and that is usable with a wide variety of beams and springs.